Oil feed restrictor

[paul21uk]

Hey guys I'm after a oil feed flange from my turbo with a 4an fitting but I can only find ones with a restrictor fitted, would it be alright to run it using a restrictor if I don't need one as I don't wanna starve the turbo of oil thanks

[FOSTA]

Can you not just drill the restrictor out?

[paul21uk]

I was thinking of doing that but wasn't to sure about it I need one by the weekend as its holding everything up

[Chris Wilson]

From the Garrett technical papers on their site:

 

 

Ball bearing turbochargers require less oil than journal bearing turbos. Therefore an oil inlet restrictor is recommended if you have oil pressure over about 60 psi. The oil outlet should be plumbed to the oil pan above the oil level (for wet sump systems). Since the oil drain is gravity fed, it is important that the oil outlet points downward, and that the drain tube does not become horizontal or go "uphill" at any point. Following a hot shutdown of a turbocharger, heat soak begins. This means that the heat in the head, exhaust manifold, and turbine housing finds it way to the turbo's center housing, raising its temperature. These extreme temperatures in the center housing can result in oil coking.

To minimize the effects of heat soak-back, water-cooled center housings were introduced. These use coolant from the engine to act as a heat sink after engine shutdown, preventing the oil from coking. The water lines utilize a thermal siphon effect to reduce the peak heat soak-back temperature after engine shut down. The layout of the pipes should minimize peaks and troughs with the (cool) water inlet on the low side. To help this along, it is advantageous to tilt the turbocharger about 25° about the axis of shaft rotation.

[paul21uk]

well dont really help mate my question is if i use a restrictor for the oil will it potentially starve the turbo as its a journal bearing this just tells me about hot shut down etc which i already no thanks anyway....

[Chris Wilson]

A journal bearing turbo uses the oil FLOW to cool the bearing area, and a fair amount of pressure is also needed to maintain a dual oil film in a high clearance bearing cassette. A ball bearing turbo needs far less oil, and far less pressure. Nonetheless, most journal bearing turbos will use SOME oil flow restriction. Example, the RB26 Skyline engines run dual turbos with journal bearings. The banjo bolt that feeds the common oil rail for the 2 turbos has a restriction in it to reduce flow. So you may need a restrictor in the line, yes. To do this correctly you need two oil pressure gauges. Proper ones, not those horrible electric ones people string down the screen pillars. Two proper bourdon tube meters. One for the oil pressure before the restriction, and for the pressure after the restriction, near the turbo(s). Add restriction until you get about a 20% pressure drop at about 4000 RPM as a guesstimate. That's assuming you see maybe 75 PSI oil pressure at 4000 RPM. You'll have 60 PSI at the turbo.

 

Or ask Garrett technical what pressure they recommend at the turbo oil inlet. If it's not a Garrett this is where you find out how good the manufacturer's technical department is. Or is not It might have helped to know what type of turbo it was you are trying to use.

[mark newman]

journal bearing no restrictor BB turbo needs a restrictor / simple

[Digsy]

From the Garrett technical papers on their site:

 

 

Ball bearing turbochargers require less oil than journal bearing turbos. Therefore an oil inlet restrictor is recommended if you have oil pressure over about 60 psi. The oil outlet should be plumbed to the oil pan above the oil level (for wet sump systems). Since the oil drain is gravity fed, it is important that the oil outlet points downward, and that the drain tube does not become horizontal or go "uphill" at any point. Following a hot shutdown of a turbocharger, heat soak begins. This means that the heat in the head, exhaust manifold, and turbine housing finds it way to the turbo's center housing, raising its temperature. These extreme temperatures in the center housing can result in oil coking.

To minimize the effects of heat soak-back, water-cooled center housings were introduced. These use coolant from the engine to act as a heat sink after engine shutdown, preventing the oil from coking. The water lines utilize a thermal siphon effect to reduce the peak heat soak-back temperature after engine shut down. The layout of the pipes should minimize peaks and troughs with the (cool) water inlet on the low side. To help this along, it is advantageous to tilt the turbocharger about 25° about the axis of shaft rotation.

 

A journal bearing turbo uses the oil FLOW to cool the bearing area, and a fair amount of pressure is also needed to maintain a dual oil film in a high clearance bearing cassette. A ball bearing turbo needs far less oil, and far less pressure. Nonetheless, most journal bearing turbos will use SOME oil flow restriction. Example, the RB26 Skyline engines run dual turbos with journal bearings. The banjo bolt that feeds the common oil rail for the 2 turbos has a restriction in it to reduce flow. So you may need a restrictor in the line, yes. To do this correctly you need two oil pressure gauges. Proper ones, not those horrible electric ones people string down the screen pillars. Two proper bourdon tube meters. One for the oil pressure before the restriction, and for the pressure after the restriction, near the turbo(s). Add restriction until you get about a 20% pressure drop at about 4000 RPM as a guesstimate. That's assuming you see maybe 75 PSI oil pressure at 4000 RPM. You'll have 60 PSI at the turbo.

 

Or ask Garrett technical what pressure they recommend at the turbo oil inlet. If it's not a Garrett this is where you find out how good the manufacturer's technical department is. Or is not It might have helped to know what type of turbo it was you are trying to use.

 

Chris, isn't it more a case of the turbo doesn't need excessive pressure, so its best to restrict it so as not to lower the pressure elsewhere in the lube circuit? i.e. if you don't restrict it, it won't actually damage the turbo - its just pointless wasting oil flow / pressure?

 

Not sure what the aftermarket world is like but most of the turbos I have seen have a pretty small oil hole feed hole machined into the centre section, anyway.

 

A word on thermo-siphoning: It will only work properly if there is an uphill run from the turbo coolant outlet to the radiator - something that I suspect many Supra turbo installs do not have.

[Chris Wilson]

There's that as well, of course, no point in wasting pressure if it's not needed, although the pump has a pretty good reserve of flow even feeding twins. A single shouldn't be an issue. The stock twins are restricted mainly by the small bore steel pipes that feed them oil. What you do NOT want is for ANY pressure to build up in the centre housing external to the bearing cassette, as friction seals will not tolerate it and it'll smoke, or at best use a lot of oil.

[paul21uk]

cheers mark thats all i needed thanks

journal bearing no restrictor BB turbo needs a restrictor / simple

[paul21uk]

well i know i wont have tech support mate they dont even have any costumer service its xspower t61 i think its worth it for now only cost 100 quid second hand just gets me rolling for a short time before i upgrade cheers for all the tech stuff mate

A journal bearing turbo uses the oil FLOW to cool the bearing area, and a fair amount of pressure is also needed to maintain a dual oil film in a high clearance bearing cassette. A ball bearing turbo needs far less oil, and far less pressure. Nonetheless, most journal bearing turbos will use SOME oil flow restriction. Example, the RB26 Skyline engines run dual turbos with journal bearings. The banjo bolt that feeds the common oil rail for the 2 turbos has a restriction in it to reduce flow. So you may need a restrictor in the line, yes. To do this correctly you need two oil pressure gauges. Proper ones, not those horrible electric ones people string down the screen pillars. Two proper bourdon tube meters. One for the oil pressure before the restriction, and for the pressure after the restriction, near the turbo(s). Add restriction until you get about a 20% pressure drop at about 4000 RPM as a guesstimate. That's assuming you see maybe 75 PSI oil pressure at 4000 RPM. You'll have 60 PSI at the turbo.

 

Or ask Garrett technical what pressure they recommend at the turbo oil inlet. If it's not a Garrett this is where you find out how good the manufacturer's technical department is. Or is not It might have helped to know what type of turbo it was you are trying to use.